How to use the Cdosys.dll library to send an e-mail message with attachments by using Visual C#


This article describes how to use the Collaboration Data Objects (CDO) for Windows 2000 library (Cdosys.dll) to send an e-mail message with attachments. You can send text or HTML or a Web page in the body of the e-mail message by using the local SMTP server or by using a smart host server in Microsoft Visual C#.

Note The Cdosys.dll library is also known as CDOSYS.

More Information

To use CDOSYS as described in the "Summary" section, follow these steps:
  1. Start Microsoft Visual Studio.
  2. On the File menu, click New, and then click Project.
  3. Under Project Types, click Visual C#, and then click Console Application under Templates. By default, Program.cs is created.

    Note In Microsoft Visual C# .NET 2003, Visual C# is changed to Visual C# Projects. By default, Class1.cs is created.
  4. Add a reference to the Microsoft CDO For Windows 2000 Library. To do this, follow these steps:
    1. On the Project menu, click Add Reference.
    2. On the COM tab, locate Microsoft CDO For Windows 2000 Library.

      Note In Visual C# .NET 2003, click Select.
    3. To accept your selections, click OK in the Add References dialog box.

      If you receive a dialog box to generate wrappers for the libraries that you selected, click Yes.
  5. In the code window, replace all the code with the following code:
    namespace CdoSys
    using System;
    class Class1
    static void Main(string[] args)
    CDO.Message oMsg = new CDO.Message();
    CDO.IConfiguration iConfg;

    iConfg = oMsg.Configuration;

    ADODB.Fields oFields;
    oFields = iConfg.Fields;

    // Set configuration.
    ADODB.Field oField = oFields[""];

    //TODO: To send by using the smart host, uncomment the following lines:
    //oField.Value = CDO.CdoSendUsing.cdoSendUsingPort;
    //oField = oFields[""];
    //oField.Value = "smarthost";

    // TODO: To send by using local SMTP service.
    //oField = oFields[""];
    //oField.Value = 1;


    // Set common properties from message.

    //TODO: To send text body, uncomment the following line:
    //oMsg.TextBody = "Hello, how are you doing?";

    //TODO: To send HTML body, uncomment the following lines:
    //String sHtml;
    //sHtml = "<HTML>\n" +
    //"<HEAD>\n" +
    //"<TITLE>Sample GIF</TITLE>\n" +
    //"</HEAD>\n" +
    //"<BODY><P>\n" +
    //"<h1><Font Color=Green>Inline graphics</Font></h1>\n" +
    //"</BODY>\n" +
    //oMsg.HTMLBody = sHtml;

    //TOTO: To send WEb page in an e-mail, uncomment the following lines and make changes in TODO section.
    //TODO: Replace with your preferred Web page
    //"", "");
    oMsg.Subject = "Test SMTP";

    //TODO: Change the To and From address to reflect your information.
    oMsg.From = "";
    oMsg.To = "";
    //ADD attachment.
    //TODO: Change the path to the file that you want to attach.
    oMsg.AddAttachment("C:\\Hello.txt", "", "");
    oMsg.AddAttachment("C:\\Test.doc", "", "");
    catch (Exception e)
    Console.WriteLine("{0} Exception caught.", e);
  6. Where TODO appears in the code, modify the code as indicated.
  7. To build and run the program, press F5.
  8. Verify that the e-mail message has been both sent and received.


For more information about Microsoft Office development with Visual Studio, see the following Microsoft Developer Network (MSDN) Web site:
For additional information about how to use CDOSYS, click the following article numbers to view the articles in the Microsoft Knowledge Base:

310221 How to use the Cdosys.dll library to embed a message in a new message by using Visual C# .NET

310224 How to use the Cdosys.dll library to process mail in the Drop directory by using Visual C# .NET

310225 How to use the Cdosys.dll Library to save a message to a file by using Visual C# .NET